Lifecycle Financing and Key-Rate-Duration Risk for Small Modular Reactor Infrastructure
This study employs a hybrid framework combining empirical key-rate-duration analysis of amortizing debt and calibrated lifecycle cost-overrun distributions to demonstrate that Small Modular Reactor projects, even at their disclosed target prices, face severe funding gaps and high default risks due to the dual pressures of construction cost escalation and interest-rate curve volatility.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Building a power plant is a gamble on the future. Before a single turbine spins or a single kilowatt of electricity is sold, developers must commit billions of dollars to construction, often over a decade or more. During this long wait, the money borrowed to build the plant is exposed to two powerful forces: the rising cost of construction materials and labor, and the shifting price of borrowing money itself. For the emerging technology of small modular reactors, which promise to be smaller and safer than traditional nuclear plants, this financial gamble has proven difficult to win. The core question facing engineers and bankers is whether the money they borrow can be paid back once the plant is running, even if the construction takes longer and costs more than anyone originally predicted.
To answer this, researchers must look at two distinct but connected problems. The first is how to measure the risk of changing interest rates. When a bank lends money for a long-term project, the value of that loan changes as interest rates move up or down. A simple way to guess this change is to assume all interest rates move together, like a single tide rising or falling. However, in reality, interest rates for short-term loans often move differently than rates for long-term loans. A more precise method, known as key-rate duration, measures how sensitive a loan is to changes at specific points along the timeline, rather than treating the entire timeline as one block. The second problem is the history of nuclear construction. Decades of data show that nuclear projects frequently run over budget and behind schedule. The challenge is to combine a precise understanding of interest rate risks with a realistic view of how much construction costs can spiral out of control.
A researcher at Ain Shams University, Ahmed Kandil, set out to test whether the precise method of measuring interest rates could help explain why some nuclear projects fail to find funding. He focused on a specific type of debt used for these projects: a thirty-year loan where the borrower pays the same amount every year, gradually paying off both interest and the original loan amount. Using a massive dataset of daily interest rate records from the United States Treasury in 2025, he compared the simple "all rates move together" method against the more detailed "key-rate" method. The results were clear and consistent. The detailed method was far more accurate at predicting how the value of the loan would change from one day to the next. In nearly every single comparison, the detailed method made a much smaller error than the simple method. This finding held true regardless of how the interest rate curves were mathematically constructed, suggesting that for long-term infrastructure loans, ignoring the specific timing of interest rate changes leads to a significant misunderstanding of risk.
The study then turned to the construction side of the equation, using a representative small modular reactor project as a test case. Instead of guessing how much a specific new project might cost overruns, the researcher looked at the hard record of 401 nuclear projects built around the world over the last century. This historical record showed a stark reality: the typical nuclear project ends up costing more than double its original estimate, and overruns are the rule rather than the exception. When this historical pattern was applied to the representative project, the financial picture became grim. Even before any construction delays or cost overruns occurred, the project could not be funded entirely by debt at the price the developers had publicly promised for the electricity. At a target price of eighty-nine dollars per megawatt-hour, the project could only support about half of its total cost through borrowing. The rest would have to come from grants, government subsidies, or the investors' own pockets.
When the researcher simulated what would happen if the project faced the typical cost increases seen in the historical record, the situation deteriorated rapidly. In a simulation of fifty thousand possible futures, the ability of the project to pay back its loans dropped below a safe level in more than ninety percent of the scenarios. The specific cost increase that caused the NuScale project to be cancelled in 2023, which many viewed as an extreme outlier, actually fell in the middle of the historical distribution of nuclear failures. It was not a rare disaster, but a common outcome. The study found that to make the project fully financeable with debt at the promised price, the interest rates would need to be impossibly low, or the price of electricity would need to be nearly double what was originally planned.
The connection between the two parts of the study is where the real danger lies. Because the detailed interest rate method showed that simple assumptions are wrong, the cost of getting the financing wrong is high. If a developer assumes interest rates will stay flat or move in a simple pattern, they might calculate that a project is safe when it is actually fragile. The study showed that a small error in guessing the interest rate environment could change the required price of electricity by nearly thirty dollars per megawatt-hour. This is a massive difference when the target price is only eighty-nine dollars. The research concludes that the financing structures currently proposed for these new reactors are not robust enough to handle the reality of nuclear construction history. The projects are being asked to succeed with a level of precision that the historical record suggests is impossible without significant government support or a willingness to pay much more for the power. The path forward requires acknowledging that the median outcome for nuclear projects is a doubling of costs, and building contracts that can survive that reality rather than hoping for the best.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.